One of the best pieces of advice I've seen here (of many very good ones!) is to get your gear together, then get your pack to fit your gear. The synthetic winter sleeping bags I used years ago wouldn't even fit in my pack now! If you had a more specific gear list and trip plan you may get some suggestions. It would also depend on whether you would resupply yourself in those 2 weeks, or carry all your food for that time. That's a fair amount of space for someone as large as yourself who needs some calories to maintain. Where and when you plan to go also brings in variables. Cold or wet is going to require more clothes and gear. I personally use a 60 liter pack the majority of the time, but my trips seldom exceed 5 days. Unless your gear list includes a UL tent and a down bag and jacket, you may find 60 is a little small. More info is good for the knowledgeable folks here to really help.